JP2002365453A - Waveguide - Google Patents

Waveguide

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Publication number
JP2002365453A
JP2002365453A JP2001172042A JP2001172042A JP2002365453A JP 2002365453 A JP2002365453 A JP 2002365453A JP 2001172042 A JP2001172042 A JP 2001172042A JP 2001172042 A JP2001172042 A JP 2001172042A JP 2002365453 A JP2002365453 A JP 2002365453A
Authority
JP
Japan
Prior art keywords
waveguide
line defect
photonic crystal
total reflection
confined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2001172042A
Other languages
Japanese (ja)
Other versions
JP3846228B2 (en
Inventor
Masatoshi Tokushima
正敏 徳島
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
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Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP2001172042A priority Critical patent/JP3846228B2/en
Priority to US10/162,764 priority patent/US6795621B2/en
Publication of JP2002365453A publication Critical patent/JP2002365453A/en
Application granted granted Critical
Publication of JP3846228B2 publication Critical patent/JP3846228B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/1225—Basic optical elements, e.g. light-guiding paths comprising photonic band-gap structures or photonic lattices

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Nanotechnology (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biophysics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optical Integrated Circuits (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a waveguide which is capable of connecting a total reflection confinement type waveguide and a photonic crystal line defect waveguide with high optical coupling efficiency. SOLUTION: The waveguide 100 is constituted by connecting the total reflection confinement type waveguide 120 to the end face of the line defect section 113 of the photonic crystal line defect waveguide 110. The photonic crystal line defect waveguide 110 is arrayed with holes 112 by photonic crystals within a high dielectric constant medium 1111 by dividing these holes to two groups in a triangular grid form and the line defect section 113 is formed at their boundary. The total reflection confinement type waveguide 120 has the same or approximately the same width as the width of the line defect section 113. The coupling loss by the reflection arising in consequence of the widths which are not the same is reduced and the optical coupling efficiency is improved.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、導波路に関し、特
に、フォトニック結晶線欠陥導波路と全反射閉じこめ型
導波路の接続部を有する構造の導波路にあって、その光
結合効率を高めるための導波路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide, and more particularly, to a waveguide having a structure having a junction between a photonic crystal line defect waveguide and a total reflection confined waveguide, and improving the optical coupling efficiency thereof. Related to a waveguide.

【０００２】[0002]

【従来の技術】フォトニック結晶（photonic crystal）
は、周期的に誘電率が大きく変調された人工光学結晶で
あり、一般に、光がそのフォトニック結晶内のどの方向
にも伝播できないフォトニック・バンド・ギャップ（Ｐ
ＢＧ）と呼ばれる角振動数帯域を有する。2. Description of the Related Art Photonic crystals
Is an artificial optical crystal in which the dielectric constant is periodically modulated to a large extent, and generally, a photonic band gap (P) in which light cannot propagate in any direction in the photonic crystal.
BG).

【０００３】図７は、２次元フォトニック結晶の構造例
を示す。この２次元三角格子フォトニック結晶体３は、
高誘電率媒質１の中に微細径のフォトニック結晶の孔２
を三角格子状に配列した構造を有している。高誘電率媒
質１には、通常、半導体（その多くは比誘電率が約１
２）が用いられる。この２次元三角格子フォトニック結
晶体３の場合、ＰＢＧが得られる孔のピッチ（または格
子定数）と孔径の組み合わせの目安は、例えば、「フォ
トニック・クリスタルズ・モデリング・ザ・フロー・オ
ブ・ライト」の１２５〜１２６頁（「Ｊ．Ｄ．Ｊｏａｎ
ｎｏｐｏｕｌｏｓ，Ｒ．Ｄ．Ｍｅａｄｅ ａｎｄ Ｊ．
Ｎ．Ｗｉｎｎ，Ｐｈｏｔｏｎｉｃ Ｃｒｙｓｔａｌｓ，
Ｍｏｄｅｌｉｎｇ ｔｈｅ Ｆｌｏｗｏｆ Ｌｉｇｈ
ｔ」Ｐｒｉｎｃｅｔｏｎ Ｕｎｉｖｅｒｓｉｔｙ Ｐｒ
ｅｓｓ、ｐｐ．１２５〜１２６）に開示されている。孔
の半径をｒ、フォトニック結晶の円孔のピッチをａ、光
の角振動数をω、真空中の光速をｃとするとき、例え
ば、誘電率１１．４の誘電体基板に三角格子状にフォト
ニック結晶の円孔を配列する場合であれば、（ｒ／ａ）
が０．４８で、｛（ω×ａ）／（２π×ｃ）｝が０．５
程度のときに、電界の振動方向と孔が伸びている向きの
関係に依らず、ＰＢＧが生じる。FIG. 7 shows an example of the structure of a two-dimensional photonic crystal. This two-dimensional triangular lattice photonic crystal 3
Holes 2 of photonic crystal of small diameter in high dielectric constant medium 1
Are arranged in a triangular lattice. The high dielectric constant medium 1 usually includes a semiconductor (most of which have a relative dielectric constant of about 1).
2) is used. In the case of the two-dimensional triangular lattice photonic crystal 3, the standard of the combination of the hole pitch (or lattice constant) and the hole diameter for obtaining PBG is, for example, “Photonic Crystals Modeling the Flow of Light, pages 125-126 ("JD Joan"
nopoulos, R .; D. Meade and J.M.
N. Winn, Photonic Crystals,
Modeling the Flowof Light
t "Princeton University Pr
ess, pp. 125-126). When the radius of the hole is r, the pitch of the circular holes of the photonic crystal is a, the angular frequency of light is ω, and the speed of light in vacuum is c, for example, a triangular lattice is formed on a dielectric substrate having a dielectric constant of 11.4. In the case of arranging circular holes of the photonic crystal in (r / a),
Is 0.48 and {(ω × a) / (2π × c)} is 0.5
In this case, PBG occurs regardless of the relationship between the vibration direction of the electric field and the direction in which the hole extends.

【０００４】図８は図７の２次元三角格子フォトニック
結晶体３を用いて作られたフォトニック結晶線欠陥導波
路の一例を示す。このフォトニック結晶線欠陥導波路５
は、図７の２次元三角格子フォトニック結晶体３の２枚
を近接配置した構造を有している。高誘電率媒質１の中
には、多数の孔２が三角格子状に配列されている。この
多数の孔２の中間部に１列の無孔部分、すなわち、線欠
陥部４が形成されている。これにより、ＰＢＧ内の角振
動数の光は、線欠陥部４以外の完全結晶部分を伝搬する
ことはできないが、線欠陥部４の部分は伝搬できるよう
になる。すなわち、この線欠陥部４は導波路として働く
ことになる。FIG. 8 shows an example of a photonic crystal line defect waveguide formed using the two-dimensional triangular lattice photonic crystal 3 of FIG. This photonic crystal line defect waveguide 5
Has a structure in which two two-dimensional triangular lattice photonic crystals 3 of FIG. In the high dielectric constant medium 1, many holes 2 are arranged in a triangular lattice. One row of non-porous portions, that is, line defect portions 4 are formed in the middle of the large number of holes 2. As a result, the light of the angular frequency in the PBG cannot propagate through the complete crystal portion other than the line defect portion 4, but can propagate through the line defect portion 4. That is, the line defect 4 functions as a waveguide.

【０００５】図８に示したフォトニック結晶線欠陥導波
路５は、光を導くだけでなく、フォトニック結晶の性質
を反映して、小さな群速度、或いは群速度の波長分散な
どの性質を示すので、この性質を利用した光デバイスの
形成が考えられる。しかしながら、フォトニック結晶線
欠陥導波路５は、光を導く導波路としての性質にのみ着
目した場合、全反射閉じ込め型導波路に劣ることがあ
る。The photonic crystal line defect waveguide 5 shown in FIG. 8 not only guides light but also exhibits properties such as a small group velocity or wavelength dispersion of the group velocity reflecting the properties of the photonic crystal. Therefore, formation of an optical device utilizing this property is conceivable. However, the photonic crystal line defect waveguide 5 may be inferior to the total reflection confined waveguide when focusing only on the property as a waveguide for guiding light.

【０００６】図９は、全反射閉じ込め型導波路の構成を
示す。この全反射閉じ込め型導波路１０は、光ファイバ
と同様に、一端に導入した光を他端に導くことができ
る。全反射閉じ込め型導波路１０は表面の滑らかな誘電
体線路であり、構造が単純で、図８のフォトニック結晶
線欠陥導波路５よりも構造揺らぎが少ないため、設計通
りの形状を作製し易い。そのため、フォトニック結晶線
欠陥導波路５よりも損失の少ない導波路を作製し易い。
しかしながら、全反射閉じ込め型導波路１０はフォトニ
ック結晶線欠陥導波路５が持つ小さい群速度、群速度の
波長分散などの性質は強くないので、全反射閉じ込め型
導波路１０とフォトニック結晶線欠陥導波路５の互いの
利点を生かすため、フォトニック結晶線欠陥導波路５と
チャネル導波路を接続することが考えられる。FIG. 9 shows a configuration of a total reflection confined waveguide. This total reflection confined waveguide 10 can guide the light introduced at one end to the other end similarly to the optical fiber. The total reflection confined waveguide 10 is a dielectric line having a smooth surface, has a simple structure, and has less structural fluctuation than the photonic crystal line defect waveguide 5 of FIG. 8, so that it is easy to produce a shape as designed. . Therefore, a waveguide having less loss than the photonic crystal line defect waveguide 5 can be easily manufactured.
However, since the total reflection confined waveguide 10 does not have strong properties such as the small group velocity and the wavelength dispersion of the group velocity of the photonic crystal line defect waveguide 5, the total reflection confinement waveguide 10 and the photonic crystal line defect are not strong. In order to take advantage of the mutual advantages of the waveguides 5, it is conceivable to connect the photonic crystal line defect waveguide 5 and the channel waveguide.

【０００７】図１０は、従来の導波路を示す。この導波
路は、図９に示した全反射閉じ込め型導波路と図８に示
したフォトニック結晶線欠陥導波路を接続した構造を有
している。図８に示した構造のフォトニック結晶線欠陥
導波路５の線欠陥部４の端面１１には、チャネル導波路
としての全反射閉じ込め型導波路１０の端面が接続され
ている。線欠陥部４の端面１１は、線欠陥部４の部分と
これ以外の部分を含めて、線欠陥部の近傍で平面であ
る。全反射閉じ込め型導波路１０の表面１２，１３とフ
ォトニック結晶線欠陥導波路５の端面１１が接続する接
続部１４，１５の角度は９０°である。全反射閉じ込め
型導波路１０の材料は、フォトニック結晶線欠陥導波路
５の高誘電率媒質１と同一の高誘電率媒質１６を用いて
いる。FIG. 10 shows a conventional waveguide. This waveguide has a structure in which the total reflection confined waveguide shown in FIG. 9 and the photonic crystal line defect waveguide shown in FIG. 8 are connected. An end face of a total reflection confined waveguide 10 as a channel waveguide is connected to an end face 11 of the line defect portion 4 of the photonic crystal line defect waveguide 5 having the structure shown in FIG. The end face 11 of the line defect 4 is a flat surface near the line defect, including the line defect 4 and other parts. The angles of the connecting portions 14 and 15 where the surfaces 12 and 13 of the total reflection confined waveguide 10 are connected to the end face 11 of the photonic crystal line defect waveguide 5 are 90 °. As the material of the total reflection confined waveguide 10, the same high dielectric constant medium 16 as the high dielectric constant medium 1 of the photonic crystal line defect waveguide 5 is used.

【０００８】全反射閉じ込め型導波路１０は、高誘電率
媒質１６で形成されているので、全反射閉じ込め型導波
路１０における光の閉じ込めが強く、全反射閉じ込め型
導波路１０を伝搬する光の横方向分布（プロファイル）
の幅は、ほぼ全反射閉じ込め型導波路１０に等しくなる
が、フォトニック結晶線欠陥導波路５を伝搬する光の幾
らかは線欠陥部４の部分から横の孔の列に広がる。その
ため、この広がった光のプロファイルに全反射閉じ込め
型導波路１０の伝搬光のプロファイルを合わせるため、
全反射閉じ込め型導波路１０の幅はフォトニック結晶線
欠陥導波路５の幅に比べて大きく設定されている。[0008] Since the total reflection confined waveguide 10 is formed of the high dielectric constant medium 16, the light is strongly confined in the total reflection confined waveguide 10, and the light propagating through the total reflection confined waveguide 10 is reduced. Lateral distribution (profile)
Is almost equal to the total reflection confined waveguide 10, but some of the light propagating through the photonic crystal line defect waveguide 5 spreads from the line defect portion 4 to the horizontal row of holes. Therefore, in order to match the profile of the propagated light of the total reflection confined waveguide 10 to the profile of the spread light,
The width of the total reflection confined waveguide 10 is set to be larger than the width of the photonic crystal line defect waveguide 5.

【０００９】[0009]

【発明が解決しようとする課題】しかし、従来の導波路
によると、全反射閉じ込め型導波路１０とフォトニック
結晶線欠陥導波路５の接続部は、全反射閉じ込め型導波
路１０の幅がフォトニック結晶線欠陥導波路５の幅に比
べて広くとられているため、全反射閉じ込め型導波路１
０の中心付近では、フォトニック結晶線欠陥導波路５の
中心付近（線欠陥部４付近）との連続性が保たれるのに
対して、全反射閉じ込め型導波路１０の中心から離れた
周辺付近では、全反射閉じ込め型導波路１０側の一様な
構造からフォトニック結晶線欠陥導波路５側の孔の周期
配列構造への接続になるため、構造上の不連続が生じ
る。フォトニック結晶自体はＰＢＧ内の角振動数の光を
透過させないので、全反射閉じ込め型導波路１０の線欠
陥部４の幅の外に分布する光の電磁界エネルギーは、フ
ォトニック結晶線欠陥導波路５の端面１１の近傍で反射
してしまい、フォトニック結晶線欠陥導波路５に入射で
きない。そのため、全反射閉じ込め型導波路１０とフォ
トニック結晶線欠陥導波路５では、伝搬光のプロファイ
ルが近いにも関わらず、光結合効率が悪いという問題が
あった。However, according to the conventional waveguide, the connecting portion between the total reflection confined waveguide 10 and the photonic crystal line defect waveguide 5 has the width of the total reflection confined waveguide 10 of the photonic crystal line defect. Since the width is larger than the width of the nick crystal line defect waveguide 5, the total reflection confined waveguide 1
In the vicinity of the center of 0, the continuity with the vicinity of the center of the photonic crystal line defect waveguide 5 (the vicinity of the line defect portion 4) is maintained, while the periphery far from the center of the total reflection confined waveguide 10 is maintained. In the vicinity, since the connection from the uniform structure on the side of the total reflection confined waveguide 10 to the periodic array of holes on the side of the photonic crystal line defect waveguide 5 is made, a structural discontinuity occurs. Since the photonic crystal itself does not transmit the light of the angular frequency in the PBG, the electromagnetic field energy of the light distributed outside the width of the line defect portion 4 of the total reflection confined waveguide 10 depends on the photonic crystal line defect conduction. The light is reflected near the end face 11 of the waveguide 5 and cannot enter the photonic crystal line defect waveguide 5. For this reason, the total reflection confined waveguide 10 and the photonic crystal line defect waveguide 5 have a problem that the optical coupling efficiency is poor, although the profile of the propagating light is close.

【００１０】したがって、本発明の目的は、全反射閉じ
込め型導波路とフォトニック結晶線欠陥導波路とを高い
光結合効率で接続することが可能な導波路を提供するこ
とにある。Accordingly, it is an object of the present invention to provide a waveguide capable of connecting a total reflection confined waveguide and a photonic crystal line defect waveguide with high optical coupling efficiency.

【００１１】[0011]

【課題を解決するための手段】本発明は、上記の目的を
達成するため、第１の特徴として、高誘電率媒質内にフ
ォトニック結晶による孔が所定のパターンで２つのグル
ープに分けて配列され、前記２つのグループの境界部に
は前記孔を有しない線欠陥部が形成されたフォトニック
結晶線欠陥導波路と、前記フォトニック結晶線欠陥導波
路の前記線欠陥部の幅と同一又は略同一の幅を有して前
記線欠陥部の端面に接続される全反射閉じ込め型導波路
を備えることを特徴とする導波路を提供する。In order to achieve the above object, the present invention has, as a first feature, holes of photonic crystals arranged in a high dielectric constant medium in a predetermined pattern in two groups. A photonic crystal line defect waveguide in which the line defect portion having no hole is formed at the boundary between the two groups, and the same or the same width as the line defect portion of the photonic crystal line defect waveguide. A waveguide having a total reflection confined waveguide having substantially the same width and connected to an end face of the line defect portion is provided.

【００１２】この構成によれば、フォトニック結晶線欠
陥導波路上に形成された線欠陥部と、これに接続される
全反射閉じ込め型導波路の幅が同一又は略同一であるた
め、フォトニック結晶線欠陥導波路と全反射閉じ込め型
導波路の接続部における反射に起因する結合損失が低減
され、光結合効率を高めることが可能になる。According to this structure, the line defect formed on the photonic crystal line defect waveguide and the total reflection confined waveguide connected thereto have the same or substantially the same width. The coupling loss due to reflection at the connection between the crystal beam defect waveguide and the total reflection confined waveguide is reduced, and the optical coupling efficiency can be increased.

【００１３】本発明は、上記の目的を達成するため、第
２の特徴として、高誘電率媒質内にフォトニック結晶に
よる孔を所定のパターンで２つのグループに分けて配列
され、前記２つのグループの境界部には前記孔を有しな
い線欠陥部が形成され、前記線欠陥部の一方の側面に沿
って配設された前記孔の内の一列のそれぞれの孔が半円
形をなすように切断加工されているフォトニック結晶線
欠陥導波路と、前記フォトニック結晶線欠陥導波路の前
記線欠陥部の幅と同一又は略同一の幅を有して前記線欠
陥部の端面に接続される全反射閉じ込め型導波路を備え
ることを特徴とする導波路を提供する。In order to achieve the above object, the present invention has, as a second characteristic, holes in a high dielectric constant medium in which a photonic crystal hole is divided into two groups in a predetermined pattern, and the two groups are arranged. A line defect having no hole is formed at a boundary of the line defect, and cut so that each line of the holes arranged along one side surface of the line defect forms a semicircle. A photonic crystal line defect waveguide being processed, and all of the photonic crystal line defect waveguides having the same or substantially the same width as the line defect portion of the photonic crystal line defect waveguide and connected to the end face of the line defect portion A waveguide provided with a reflective confinement waveguide is provided.

【００１４】この構成によれば、フォトニック結晶線欠
陥導波路上に形成された線欠陥部と、これに接続される
全反射閉じ込め型導波路の幅が同一又は略同一であるた
め、フォトニック結晶線欠陥導波路と全反射閉じ込め型
導波路の接続部における反射に起因する結合損失が低減
され、光結合効率を高めることが可能になる。更に、フ
ォトニック結晶線欠陥導波路は、全反射閉じ込め型導波
路を接続する側の側面に沿うフォトニック結晶の一列が
半円形に切断されているため、線欠陥部の端面が幅方向
に広がりを持たない構造になり、フォトニック結晶表面
への漏洩による損失が低減する。According to this configuration, the width of the line defect formed on the photonic crystal line defect waveguide and the width of the total reflection confined waveguide connected thereto are the same or substantially the same. The coupling loss due to reflection at the connection between the crystal beam defect waveguide and the total reflection confined waveguide is reduced, and the optical coupling efficiency can be increased. Furthermore, in the photonic crystal line defect waveguide, since a row of photonic crystals along the side surface on the side connecting the total reflection confined waveguide is cut into a semicircle, the end face of the line defect part spreads in the width direction. And the loss due to leakage to the photonic crystal surface is reduced.

【００１５】本発明は、上記の目的を達成するため、第
３の特徴として、所定の幅と長さを有する全反射閉じ込
め型導波路と、高誘電率媒質内にフォトニック結晶によ
る孔が所定のパターンで２つのグループに分けて配列さ
れると共に、前記全反射閉じ込め型導波路の幅と同一又
は略同一な幅を有して前記孔を有しない線欠陥部が前記
２つのグループの境界部に形成され、前記線欠陥部に前
記全反射閉じ込め型導波路の一端が接続され、前記全反
射閉じ込め型導波路の両側に前記高誘電率媒質を突出さ
せて保護部が形成されているフォトニック結晶線欠陥導
波路を備えることを特徴とする導波路を提供する。In order to achieve the above object, the present invention has, as a third feature, a total reflection confined waveguide having a predetermined width and length, and a hole made of a photonic crystal in a high dielectric constant medium. And a line defect portion having the same or substantially the same width as that of the total reflection confined waveguide and having no hole is provided at a boundary portion between the two groups. A photonic, wherein one end of the total reflection confined waveguide is connected to the line defect portion, and a protective portion is formed by projecting the high dielectric constant medium on both sides of the total reflection confined waveguide. A waveguide provided with a crystal defect waveguide is provided.

【００１６】この構成によれば、フォトニック結晶線欠
陥導波路上に形成された線欠陥部と、これに接続される
全反射閉じ込め型導波路の幅が同一又は略同一であるた
め、フォトニック結晶線欠陥導波路と全反射閉じ込め型
導波路の接続部における反射に起因する結合損失が低減
され、光結合効率を高めることが可能になる。更に、全
反射閉じ込め型導波路の両側を埋める如くに保護部が形
成されているため、光結合損失が低減すると同時に、接
合部近傍のフォトニック結晶の機械的強度を増すことが
できる。According to this configuration, the width of the line defect formed on the photonic crystal line defect waveguide and the width of the total reflection confined waveguide connected thereto are the same or substantially the same. The coupling loss due to reflection at the connection between the crystal beam defect waveguide and the total reflection confined waveguide is reduced, and the optical coupling efficiency can be increased. Furthermore, since the protection portion is formed so as to fill both sides of the total reflection confined waveguide, the optical coupling loss can be reduced and the mechanical strength of the photonic crystal near the junction can be increased.

【００１７】[0017]

【発明の実施の形態】以下、本発明の実施の形態につい
て図面を基に説明する。図１は、本発明の第１の実施形
態を示す。本実施の形態による導波路は、２次元三角格
子フォトニック結晶による線欠陥導波路と全反射閉じ込
め型導波路を接続して構成されている。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. The waveguide according to the present embodiment is configured by connecting a line defect waveguide made of a two-dimensional triangular lattice photonic crystal and a total reflection confined waveguide.

【００１８】本発明の導波路１００は、フォトニック結
晶線欠陥導波路１１０と全反射閉じ込め型導波路１２０
からなり、全反射閉じ込め型導波路１２０はフォトニッ
ク結晶線欠陥導波路１１０の端面１３０に、これと一直
線上になる様に接続されている。フォトニック結晶線欠
陥導波路１１０は、母体媒質（高誘電率媒質）１１１
と、この中に三角格子状に配列された多数のフォトニッ
ク結晶の孔１１２が設けられた構成になっている。ただ
し、母体媒質１１１の中間部の所定幅には孔１１２は設
けられておらず、この部分には線欠陥部１１３が形成さ
れている。母体媒質１１１には、半導体（一般には、比
誘電率が約１２のシリコン）が用いられる。全反射閉じ
込め型導波路１２０は母体媒質１１１と同一の材料が用
いられ、その幅Ｗは線欠陥部１１３とほぼ同一にされ
る。The waveguide 100 of the present invention comprises a photonic crystal beam defect waveguide 110 and a total reflection confined waveguide 120.
The total reflection confined waveguide 120 is connected to the end face 130 of the photonic crystal line defect waveguide 110 so as to be in line with the end face 130. The photonic crystal line defect waveguide 110 includes a host medium (high dielectric constant medium) 111
And a large number of photonic crystal holes 112 arranged in a triangular lattice. However, the hole 112 is not provided in a predetermined width of the intermediate portion of the base medium 111, and a line defect portion 113 is formed in this portion. For the base medium 111, a semiconductor (generally, silicon having a relative dielectric constant of about 12) is used. The total reflection confined waveguide 120 is made of the same material as the base medium 111, and has a width W substantially equal to that of the line defect portion 113.

【００１９】全反射閉じ込め型導波路１２０は、その一
端面が線欠陥部１１３の側面（端面１３０）に接続され
るが、線欠陥部１１３とは一直線上（同一軸線上）にな
り、かつ同一平面になるように接続される。そして、全
反射閉じ込め型導波路１２０の表面（側面）１２１，１
２２と端面１３０は直角または、ほぼ直角になってい
る。One end face of the total reflection confined waveguide 120 is connected to the side face (end face 130) of the line defect part 113, but is aligned with the line defect part 113 (on the same axis) and is the same. It is connected so that it may become a plane. The surface (side surface) 121, 1 of the total reflection confined waveguide 120
22 and the end face 130 are at right angles or almost at right angles.

【００２０】図１の構成においては、全反射閉じ込め型
導波路１２０の幅Ｗとフォトニック結晶線欠陥導波路１
１０の線欠陥部１１３の幅がほぼ等しく、かつ、材料が
同一で連続している。このため、全反射閉じ込め型導波
路１２０を伝搬してきた光は、殆ど全てがフォトニック
結晶線欠陥導波路１１０の線欠陥部１１３に入光する。
線欠陥部１１３の部分に入った光は、周囲に配列された
孔１１２で回折されるが、この回折によって全反射閉じ
込め型導波路１２０からの伝搬光の入射方向と逆向きに
回折され、全反射閉じ込め型導波路１２０に反射光とし
て戻る光の割合は、伝搬光のプロファイルを合わせるこ
とを優先した図９の構造よりも小さくなり、結果として
光結合効率は本発明の方が高くなる。In the configuration shown in FIG. 1, the width W of the total reflection confined waveguide 120 and the photonic crystal defect waveguide 1
The widths of the ten line defect portions 113 are substantially equal, and the materials are the same and continuous. Therefore, almost all of the light propagating through the total reflection confined waveguide 120 enters the line defect portion 113 of the photonic crystal line defect waveguide 110.
The light that has entered the line defect portion 113 is diffracted by the holes 112 arranged on the periphery, and is diffracted in the direction opposite to the incident direction of the propagating light from the total reflection confined waveguide 120 by this diffraction. The ratio of light returning as reflected light to the reflective confinement waveguide 120 is smaller than that of the structure of FIG. 9 in which priority is given to matching the profile of propagating light, and as a result, the optical coupling efficiency is higher in the present invention.

【００２１】〔実施例〕ここで、第１の実施の形態に対
応した実施例について説明する。フォトニック結晶線欠
陥導波路１１０の母体材料（母体媒質１１１）として誘
電率１１．４のシリコン（Ｓｉ）を用い、三角格子（孔
１１２）のピッチを０．７μｍ、孔１１２の直径を０．
６４μｍとし、更に、線欠陥部１１３の幅を０．５７μ
ｍとした。全反射閉じ込め型導波路１２０の幅Ｗは、線
欠陥部１１３の幅と同じ０．５７μｍとした。また、フ
ォトニック結晶線欠陥導波路１１０の端面１３０と、こ
の端面１３０に最も近い孔１１２との間の距離（領域１
１４，１１５）を０．０６μｍとした。Example An example corresponding to the first embodiment will now be described. Silicon (Si) having a dielectric constant of 11.4 is used as a base material (base medium 111) of the photonic crystal line defect waveguide 110, the pitch of the triangular lattice (holes 112) is 0.7 μm, and the diameter of the holes 112 is 0.1 μm.
64 μm, and the width of the line defect portion 113 is set to 0.57 μm.
m. The width W of the total reflection confined waveguide 120 was set to 0.57 μm, which is the same as the width of the line defect portion 113. Further, the distance between the end face 130 of the photonic crystal line defect waveguide 110 and the hole 112 closest to the end face 130 (region 1).
14, 115) was set to 0.06 μm.

【００２２】上記した各部の寸法のもとに、数値計算シ
ミュレーションを実施した。その結果、ＰＢＧ内の角振
動数を有する光に対して、フォトニック結晶線欠陥導波
路１１０と全反射閉じ込め型導波路１２０の結合損失と
して、０．５ｄＢが得られた。全反射閉じ込め型導波路
１２０の幅を２．２μｍとし、他の構造や数値は同じと
した従来構造の場合、同じ角振動数の光に対して２．３
ｄＢの結合損失があり、このことから、本発明により、
１．８ｄＢ改善できることがわかった。A numerical simulation was performed based on the dimensions of each part described above. As a result, for light having an angular frequency in the PBG, 0.5 dB was obtained as a coupling loss between the photonic crystal line defect waveguide 110 and the total reflection confined waveguide 120. In the case of a conventional structure in which the width of the total reflection confined waveguide 120 is 2.2 μm and other structures and numerical values are the same, 2.3 for light having the same angular frequency.
There is a coupling loss of dB, from which, according to the invention,
It was found that 1.8 dB could be improved.

【００２３】図２は、図１の導波路の変形例を示す。図
２においては、図１と同一であるものには同一引用数字
を用いたので、重複する説明は省略する。図１において
は、線欠陥部１１３と全反射閉じ込め型導波路１２０の
接続角は０°、すなわち一直線であったが、本実施の形
態では、或る角度θを持たせている。導波路の幅方向の
波数分布が、全反射閉じ込め型導波路１２０とフォトニ
ック結晶線欠陥導波路１１０で異なる場合、このように
角度θを設けることによって一致性が向上し、光結合効
率が向上する場合がある。FIG. 2 shows a modification of the waveguide of FIG. In FIG. 2, the same reference numerals are used for the same components as those in FIG. In FIG. 1, the connection angle between the line defect portion 113 and the total reflection confined waveguide 120 is 0 °, that is, a straight line. However, in the present embodiment, a certain angle θ is provided. When the wave number distribution in the width direction of the waveguide is different between the total reflection confined waveguide 120 and the photonic crystal line defect waveguide 110, providing the angle θ in this way improves the coherence and improves the optical coupling efficiency. May be.

【００２４】図３は、本発明の第２の実施の形態を示
す。本実施の形態においても、図３においては、図１と
同一であるものには同一引用数字を用いたので、ここで
は重複する説明を省略する。上記第１の実施の形態の構
造においては、フォトニック結晶線欠陥導波路１１０の
端面１３０と、この端面１３０に最も近い孔１１２ａ，
１１２ｂとの間の距離は、全反射閉じ込め型導波路１２
０とフォトニック結晶線欠陥導波路１１０の光結合効率
を向上させるために重要である。この距離が大きくなる
と、全反射閉じ込め型導波路１２０とフォトニック結晶
線欠陥導波路１１０の線欠陥部１１３までの距離が遠く
なり、全反射閉じ込め型導波路１２０を伝搬してきた光
の一部が、端面１３０と最も近い孔１１２ａ，１１２ｂ
の列との間の領域１１４，１１５に回り込み、光結合効
率を低下させる。この問題を解決するのが、図３に示す
第２の実施の形態である。FIG. 3 shows a second embodiment of the present invention. Also in the present embodiment, in FIG. 3, the same reference numerals are used for the same components as those in FIG. 1, and the duplicate description is omitted here. In the structure of the first embodiment, the end face 130 of the photonic crystal line defect waveguide 110 and the holes 112a,
112b is the total reflection confined waveguide 12
0 is important for improving the optical coupling efficiency of the photonic crystal line defect waveguide 110. When this distance increases, the distance between the total reflection confined waveguide 120 and the line defect portion 113 of the photonic crystal line defect waveguide 110 increases, and part of the light propagating through the total reflection confinement waveguide 120 becomes smaller. Holes 112a and 112b closest to the end face 130
Wrap around the regions 114 and 115 between the columns and reduce the optical coupling efficiency. The second embodiment shown in FIG. 3 solves this problem.

【００２５】図３に示すように、線欠陥部１１３を含む
フォトニック結晶、即ち、フォトニック結晶線欠陥導波
路１４０の端面１４１は、線欠陥部１１３と交差し、か
つ、フォトニック結晶線欠陥導波路１４０の全反射閉じ
込め型導波路１２０に寄った各孔１１２を横切るように
切断する面である。全反射閉じ込め型導波路１２０は、
その端面１４１の線欠陥部１１３の部分に接続されてい
る。全反射閉じ込め型導波路１２０の幅Ｗは、線欠陥部
１１３の幅に等しくし、或いはほぼ等しくしている。端
面１４１の線欠陥部１１３の部分の両脇に位置する半円
孔の表面１４２，１４３は、全反射閉じ込め型導波路１
２０の表面１２１，１２２と滑らかに接続されている。As shown in FIG. 3, the photonic crystal including the line defect portion 113, that is, the end face 141 of the photonic crystal line defect waveguide 140 crosses the line defect portion 113 and has a photonic crystal line defect. This is a surface that is cut so as to cross each hole 112 of the waveguide 140 that approaches the total reflection confined waveguide 120. The total reflection confined waveguide 120 is
The end surface 141 is connected to the line defect portion 113. The width W of the total reflection confined waveguide 120 is equal to or approximately equal to the width of the line defect portion 113. The surfaces 142 and 143 of the semicircular holes located on both sides of the line defect portion 113 of the end face 141 are the total reflection confined waveguide 1
20 and are smoothly connected to the surfaces 121 and 122.

【００２６】図３の実施の形態によれば、フォトニック
結晶線欠陥導波路１４０の全反射閉じ込め型導波路１２
０に接続される端面１４１が側面方向（線欠陥部１１３
の幅方向又は図の上下方向）に広がりを持たない構造に
なり、全反射閉じ込め型導波路１２０の伝搬光の一部が
フォトニック結晶線欠陥導波路１４０の線欠陥部１１３
の脇の結晶表面に漏れることがないため、光結合損失が
向上する。According to the embodiment of FIG. 3, the total reflection confined waveguide 12 of the photonic crystal line defect waveguide 140 is used.
0 is connected to the side surface (line defect portion 113).
(The width direction or the vertical direction in the figure) of the photonic crystal line defect waveguide 140.
Since there is no leakage to the crystal surface beside the above, the optical coupling loss is improved.

【００２７】図４は、図３の導波路の変形例を示す。図
４においては、図１〜図３に示したと同一であるものに
は同一引用数字を用いたので、ここでは重複する説明を
省略する。図３においては、線欠陥部１１３と全反射閉
じ込め型導波路１２０の接続角は０°、即ち一直線であ
るが、図４に示すように、角度θを持たせることによ
り、図２と同様に、導波路の幅方向の波数分布が、全反
射閉じ込め型導波路１２０とフォトニック結晶線欠陥導
波路１４０で異なる場合、このように角度θを設けるこ
とにより、光結合効率が向上する場合がある。FIG. 4 shows a modification of the waveguide of FIG. In FIG. 4, the same reference numerals are used for the same components as those shown in FIGS. 1 to 3, and thus, redundant description will be omitted here. In FIG. 3, the connection angle between the line defect portion 113 and the total reflection confined waveguide 120 is 0 °, that is, a straight line. However, as shown in FIG. When the wave number distribution in the width direction of the waveguide is different between the total reflection confined waveguide 120 and the photonic crystal line defect waveguide 140, the optical coupling efficiency may be improved by providing the angle θ in this manner. .

【００２８】ここで、本発明の第２の実施の形態に対応
した実施例について説明する。フォトニック結晶線欠陥
導波路１４０の母体材料（母体媒質）として誘電率１
１．４のシリコン（Ｓｉ）を用い、三角格子（孔１１
２）のピッチを０．７μｍ、孔１１２の直径を０．６４
μｍとした。このとき、線欠陥部１１３の幅は０．５７
μｍとした。全反射閉じ込め型導波路１２０の幅Ｗは、
線欠陥部１１３の幅と同一の０．５７μｍとした。Here, an example corresponding to the second embodiment of the present invention will be described. As a base material (base medium) of the photonic crystal line defect waveguide 140, a dielectric constant of 1
Using a silicon (Si) of 1.4, a triangular lattice (hole 11
2) The pitch is 0.7 μm and the diameter of the hole 112 is 0.64.
μm. At this time, the width of the line defect portion 113 is 0.57
μm. The width W of the total reflection confined waveguide 120 is
The width was 0.57 μm, which was the same as the width of the line defect 113.

【００２９】上記した各部の寸法のもとに、数値計算シ
ミュレーションを実施した。ＰＢＧ内の角振動数を有す
る光に対して、フォトニック結晶線欠陥導波路１４０と
全反射閉じ込め型導波路１２０の結合損失として、０．
３ｄＢが得られた。上記第１の実施の形態で得られた結
合損失０．５ｄＢに対し、本実施の形態では結合損失が
０．２ｄＢ改善されていた。Numerical simulations were performed based on the dimensions of the above-described parts. For light having an angular frequency in the PBG, the coupling loss between the photonic crystal line defect waveguide 140 and the total reflection confined waveguide 120 is set to 0.
3 dB was obtained. In contrast to the coupling loss of 0.5 dB obtained in the first embodiment, the present embodiment has improved the coupling loss by 0.2 dB.

【００３０】図３において、全反射閉じ込め型導波路１
２０とフォトニック結晶線欠陥導波路１４０の接続部
は、端面１４１の線欠陥部１１３以外の部分においてフ
ォトニック結晶の劈開面が露出した構造になっている。
これは図４においても同様である。このように、フォト
ニック結晶の劈開面が露出した構造は、機械的強度が弱
いことが問題になることがある。これを解決する構造に
ついて次に説明する。In FIG. 3, a total reflection confined waveguide 1 is shown.
The connection between the photonic crystal line waveguide 20 and the photonic crystal line defect waveguide 140 has a structure in which the cleavage plane of the photonic crystal is exposed at a portion other than the line defect portion 113 on the end face 141.
This is the same in FIG. As described above, the structure in which the cleavage plane of the photonic crystal is exposed may have a problem that the mechanical strength is weak. A structure for solving this will be described below.

【００３１】図５は、本発明の第３の実施の形態を示
し、フォトニック結晶の劈開面の機械的強度を高めた導
波路となっている。図５の構造は、図１（又は図３）の
構造において、全反射閉じ込め型導波路１２０との接続
部以外のフォトニック結晶の周囲に孔１１２の無い、母
体媒質１１１のみの周辺保護部１５１，１５２を付加し
てフォトニック結晶線欠陥導波路１５０を形成してい
る。この周辺保護部１５１，１５２の機械的強度は、孔
の有るフォトニック結晶部分よりも高いので、フォトニ
ック結晶部分を破損から保護することができる。FIG. 5 shows a third embodiment of the present invention, which is a waveguide in which the mechanical strength of the cleavage plane of the photonic crystal is increased. The structure shown in FIG. 5 is different from the structure shown in FIG. 1 (or FIG. 3) in that there is no hole 112 around the photonic crystal other than the connection with the total reflection confined waveguide 120, and the peripheral protection portion 151 only includes the base medium 111. , 152 are added to form a photonic crystal line defect waveguide 150. Since the mechanical strength of the peripheral protection portions 151 and 152 is higher than that of the photonic crystal portion having holes, the photonic crystal portion can be protected from damage.

【００３２】更に、図５の構造には、図３の接続部の構
造よりも光結合損失を低減するための工夫が施されてい
る。図５のＡ−Ａ’面から右側は、図３に示すフォトニ
ック結晶線欠陥導波路１４０と同じであるが、図５で
は、Ａ−Ａ’面、即ち、全反射閉じ込め型導波路１２０
とフォトニック結晶線欠陥導波路１５０が接続されてい
る位置を通る面よりも全反射閉じ込め型導波路１２０の
側（図５の左側）にもフォトニック結晶の孔１５３の複
数個を周辺保護部１５１，１５２の付け根部に設けてい
る。Further, the structure of FIG. 5 is devised to reduce the optical coupling loss as compared with the structure of the connecting portion of FIG. The right side from the AA ′ plane in FIG. 5 is the same as the photonic crystal line defect waveguide 140 shown in FIG. 3, but in FIG. 5, the AA ′ plane, that is, the total reflection confined waveguide 120 is shown.
A plurality of holes 153 of the photonic crystal are also provided on the side of the total reflection confined waveguide 120 (left side in FIG. 5) with respect to the plane passing through the position where the waveguide 150 and the photonic crystal line defect waveguide 150 are connected. It is provided at the base of 151 and 152.

【００３３】このようにすると、全反射閉じ込め型導波
路１２０からの光は、線欠陥部１１３に入った後、線欠
陥部１１３の周囲に配列された孔１１２で回折され、線
欠陥部１１３の両側に配列された孔１１２を通り抜け、
全反射閉じ込め型導波路１２０の側の表面から放射して
いく光の割合が低減される。これにより、フォトニック
結晶線欠陥導波路１５０と全反射閉じ込め型導波路１２
０の接続部の光結合損失を低減できる。In this way, the light from the total reflection confined waveguide 120 enters the line defect portion 113, is diffracted by the holes 112 arranged around the line defect portion 113, and Through the holes 112 arranged on both sides,
The proportion of light radiating from the surface on the side of the total reflection confined waveguide 120 is reduced. Thus, the photonic crystal line defect waveguide 150 and the total reflection confined waveguide 12
It is possible to reduce the optical coupling loss of the connection part of No. 0.

【００３４】ここで、本発明の図５の構造に対応した実
施例について説明する。フォトニック結晶線欠陥導波路
１５０の母体材料（母体媒質）を誘電率１１．４のシリ
コン（Ｓｉ）、三角格子（孔１１２）のピッチを０．７
μｍ、孔１１２の直径を０．６４μｍ、線欠陥３の幅を
０．５７μｍとした。上記した各部の寸法のもとに、数
値計算シミュレーションを実施した。その結果、結合損
失として０．２ｄＢが得られた。これは、先に述べた本
発明の第２の実施の形態における結合損失０．３ｄＢか
ら、更に、結合損失を０．１ｄＢ低減できたことにな
る。Here, an embodiment corresponding to the structure of FIG. 5 of the present invention will be described. The base material (base medium) of the photonic crystal line defect waveguide 150 is silicon (Si) having a dielectric constant of 11.4, and the pitch of the triangular lattice (hole 112) is 0.7.
μm, the diameter of the hole 112 was 0.64 μm, and the width of the line defect 3 was 0.57 μm. Numerical simulation was performed based on the dimensions of the above-described parts. As a result, 0.2 dB was obtained as the coupling loss. This means that the coupling loss can be further reduced by 0.1 dB from the coupling loss of 0.3 dB in the above-described second embodiment of the present invention.

【００３５】図５においても、全反射閉じ込め導波路１
２０をフォトニック結晶線欠陥導波路１５０に対して図
２又は図４に示したように、斜めに接続し、更に結合損
失を低減することができる。Also in FIG. 5, the total reflection confined waveguide 1
As shown in FIG. 2 or FIG. 4, 20 can be connected obliquely to the photonic crystal line defect waveguide 150 to further reduce the coupling loss.

【００３６】上記各実施の形態においては、２次元フォ
トニック結晶について述べたが、本発明は、擬似的な２
次元フォトニック結晶であるスラブ型フォトニック結晶
にも適用できることは言うもまでもない。このとき、全
反射閉じこめ型導波路も有限の厚みを持つので、特にチ
ャネル導波路と呼ばれる。In each of the above embodiments, a two-dimensional photonic crystal has been described.
Needless to say, the present invention can be applied to a slab type photonic crystal which is a two-dimensional photonic crystal. At this time, since the total reflection confined waveguide also has a finite thickness, it is particularly called a channel waveguide.

【００３７】図６は、スラブ型フォトニック結晶の構造
を示す。図中、６０は母体媒質であり、６１は孔、６２
は劈開面を示す。この様な有限の厚みを有するフォトニ
ック結晶の場合でも、本発明による全反射閉じ込め型導
波路とフォトニック結晶線欠陥導波路の接続部の断面
は、２次元フォトニック結晶の場合と同じである。FIG. 6 shows the structure of a slab type photonic crystal. In the figure, 60 is a parent medium, 61 is a hole, 62
Indicates a cleavage plane. Even in the case of the photonic crystal having such a finite thickness, the cross section of the connection portion between the total reflection confined waveguide according to the present invention and the photonic crystal line defect waveguide is the same as that of the two-dimensional photonic crystal. .

【００３８】また、上記実施の形態においては、三角格
子フォトニック結晶について述べたが、正方格子や長方
格子や斜方格子などのフォトニック結晶の格子の形態が
三角格子から微妙に異なる格子のフォトニック結晶につ
いても本発明を適用できることは明らかである。In the above embodiment, the description has been given of the triangular lattice photonic crystal. However, the lattice form of the photonic crystal such as a square lattice, a rectangular lattice, and an oblique lattice is slightly different from the triangular lattice. It is clear that the present invention can be applied to a photonic crystal.

【００３９】さらに、フォトニック結晶線欠陥導波路の
線欠陥部は、一列のみの線欠陥としたが、２列以上の幅
の広い線欠陥についても本発明が適用できることは言う
までもない。また、上記各実施例においては、シリコン
（Ｓｉ）を母体材料（母体媒質）として用いたが、他の
材料、特に、化合物半導体を用いてもよいことは言うま
でもない。Further, the line defect portion of the photonic crystal line defect waveguide is a line defect of only one line, but it is needless to say that the present invention can be applied to a line defect having a width of two or more lines. Further, in each of the above embodiments, silicon (Si) is used as the base material (base medium), but it is needless to say that other materials, in particular, a compound semiconductor may be used.

【００４０】[0040]

【発明の効果】以上説明したように、本発明の導波路に
よれば、フォトニック結晶線欠陥導波路に全反射閉じ込
め型導波路を接続して構成される導波路において、フォ
トニック結晶線欠陥導波路上に形成された線欠陥部と、
これに接続される全反射閉じ込め型導波路の幅を同一又
は略同一にしたため、フォトニック結晶線欠陥導波路と
全反射閉じ込め型導波路の接続部における反射に起因す
る結合損失が低減され、光結合効率を高めることが可能
になる。As described above, according to the waveguide of the present invention, in a waveguide formed by connecting a total reflection confined waveguide to a photonic crystal line defect waveguide, a photonic crystal line defect A line defect formed on the waveguide;
Since the width of the total reflection confined waveguide connected thereto is the same or substantially the same, the coupling loss due to reflection at the connection between the photonic crystal line defect waveguide and the total reflection confined waveguide is reduced, and the light It is possible to increase the coupling efficiency.

【００４１】また、本発明の他の導波路によれば、フォ
トニック結晶線欠陥導波路上に形成された線欠陥部と、
これに接続される全反射閉じ込め型導波路の幅を同一又
は略同一にし、フォトニック結晶線欠陥導波路と全反射
閉じ込め型導波路の接続部における反射に起因する結合
損失を低減した構造にしたため、光結合効率を高めるこ
とが可能になる。更に、フォトニック結晶線欠陥導波路
は、全反射閉じ込め型導波路を接続する側の側面に沿う
フォトニック結晶の一列が半円形に切断された構造にし
たため、線欠陥部の端面が幅方向に広がりを持たない構
造になり、フォトニック結晶表面への漏洩による損失を
低減できる。According to another waveguide of the present invention, there is provided a line defect portion formed on a photonic crystal line defect waveguide,
The width of the total reflection confined waveguide connected to this is made the same or almost the same, and the coupling loss due to reflection at the connection between the photonic crystal line defect waveguide and the total reflection confined waveguide is reduced. , It is possible to increase the optical coupling efficiency. Furthermore, since the photonic crystal line defect waveguide has a structure in which a row of photonic crystals along the side surface connecting the total reflection confined waveguide is cut into a semicircle, the end face of the line defect portion is in the width direction. The structure has no spread, and loss due to leakage to the photonic crystal surface can be reduced.

【００４２】さらに、本発明の他の導波路によれば、フ
ォトニック結晶線欠陥導波路上に形成された線欠陥部
と、これに接続される全反射閉じ込め型導波路の幅が同
一であるため、フォトニック結晶線欠陥導波路と全反射
閉じ込め型導波路の接続部における反射に起因する結合
損失が低減され、光結合効率を高めることが可能にな
る。更に、全反射閉じ込め型導波路の両側を埋めるよう
に保護部を形成したことにより、光結合損失が低減する
と同時に、接合部近傍のフォトニック結晶の機械的強度
を増すことができる。Further, according to another waveguide of the present invention, the width of the line defect formed on the photonic crystal line defect waveguide and the total reflection confined waveguide connected thereto are the same. Therefore, the coupling loss due to reflection at the connection between the photonic crystal line defect waveguide and the total reflection confined waveguide is reduced, and the optical coupling efficiency can be increased. Further, by forming the protective portion so as to fill both sides of the total reflection confined waveguide, the optical coupling loss can be reduced and the mechanical strength of the photonic crystal near the junction can be increased.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の第１の実施形態を示す断面図である。FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

【図２】図１の導波路の変形例を示す断面図である。FIG. 2 is a sectional view showing a modification of the waveguide of FIG. 1;

【図３】本発明の第２の実施の形態を示す断面図であ
る。FIG. 3 is a sectional view showing a second embodiment of the present invention.

【図４】図３の導波路の変形例を示す断面図である。FIG. 4 is a sectional view showing a modification of the waveguide of FIG. 3;

【図５】本発明の第３の実施の形態を示す断面図であ
る。FIG. 5 is a sectional view showing a third embodiment of the present invention.

【図６】スラブ型フォトニック結晶を示す斜視図であ
る。FIG. 6 is a perspective view showing a slab type photonic crystal.

【図７】２次元フォトニック結晶の構造例を示す断面図
である。FIG. 7 is a cross-sectional view illustrating a structural example of a two-dimensional photonic crystal.

【図８】フォトニック結晶線欠陥導波路の一例を示す断
面図である。FIG. 8 is a sectional view showing an example of a photonic crystal line defect waveguide.

【図９】全反射閉じ込め型導波路の構成を示す断面図で
ある。FIG. 9 is a cross-sectional view illustrating a configuration of a total reflection confined waveguide.

【図１０】従来の導波路を示す断面図である。FIG. 10 is a cross-sectional view showing a conventional waveguide.

【符号の説明】[Explanation of symbols]

１ 高誘電率媒質 ２ フォトニック結晶の孔 ３ ２次元三角格子フォトニック結晶 ４ 線欠陥部 ５ フォトニック結晶線欠陥導波路 １０ 全反射閉じ込め型導波路 １００ 導波路 １１０，１４０，１５０ フォトニック結晶線欠陥導波
路 １１１ 母体媒質（高誘電率媒質） １１２，１１２ａ，１１２ｂ，１５３ 孔 １１３ 線欠陥部 １２０ 全反射閉じ込め型導波路 １３０，１４１ 端面 １５１，１５２ 周辺保護部DESCRIPTION OF SYMBOLS 1 High dielectric constant medium 2 Photonic crystal hole 3 Two-dimensional triangular lattice photonic crystal 4 Line defect part 5 Photonic crystal line defect waveguide 10 Total reflection confinement type waveguide 100 Waveguide 110, 140, 150 Photonic crystal line Defect waveguide 111 Base medium (high dielectric constant medium) 112, 112a, 112b, 153 Hole 113 Line defect part 120 Total reflection confined waveguide 130, 141 End face 151, 152 Peripheral protection part

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 高誘電率媒質内にフォトニック結晶によ
る孔が所定のパターンで２つのグループに分けて配列さ
れ、前記２つのグループの境界部には前記孔を有しない
線欠陥部が形成されたフォトニック結晶線欠陥導波路
と、 前記フォトニック結晶線欠陥導波路の前記線欠陥部の幅
と同一又は略同一の幅を有して前記線欠陥部の端面に接
続される全反射閉じ込め型導波路を備えることを特徴と
する導波路。In a high dielectric constant medium, holes made of a photonic crystal are arranged in two groups in a predetermined pattern, and a line defect having no holes is formed at a boundary between the two groups. A photonic crystal line defect waveguide, and a total reflection confinement type having the same or substantially the same width as the width of the line defect portion of the photonic crystal line defect waveguide and connected to an end face of the line defect portion. A waveguide comprising a waveguide. 【請求項２】 前記全反射閉じ込め型導波路は、前記線
欠陥部と同一軸線上に配置して接続され、或いは、前記
線欠陥部の軸線に対して角度をもって接続されているこ
とを特徴とする請求項１記載の導波路。2. The total reflection confined waveguide is arranged and connected on the same axis as the line defect, or connected at an angle to the axis of the line defect. 2. The waveguide according to claim 1, wherein: 【請求項３】 高誘電率媒質内にフォトニック結晶によ
る孔が所定のパターンで２つのグループに分けて配列さ
れ、前記２つのグループの境界部には前記孔を有しない
線欠陥部が形成され、前記線欠陥部の一方の側面に沿っ
て配設された前記孔の内の一列のそれぞれの孔が半円形
をなすように切断加工されているフォトニック結晶線欠
陥導波路と、 前記フォトニック結晶線欠陥導波路の前記線欠陥部の幅
と同一又は略同一の幅を有して前記線欠陥部の端面に接
続される全反射閉じ込め型導波路を備えることを特徴と
する導波路。3. A high-dielectric medium in which holes made of a photonic crystal are arranged in a predetermined pattern in two groups, and a line defect having no holes is formed at a boundary between the two groups. A photonic crystal line defect waveguide in which one row of the holes arranged along one side surface of the line defect portion is cut so as to form a semicircle; A waveguide comprising a total reflection confined waveguide having the same or substantially the same width as the width of the line defect portion of the crystal defect waveguide and connected to an end face of the line defect portion. 【請求項４】 前記全反射閉じ込め型導波路は、前記線
欠陥部と同一軸線上に配置して接続され、或いは、前記
線欠陥部の軸線に対して角度をもって接続されているこ
とを特徴とする請求項３記載の導波路。4. The total reflection confined waveguide is arranged and connected on the same axis as the line defect, or connected at an angle to the axis of the line defect. The waveguide according to claim 3, wherein 【請求項５】 所定の幅と長さを有する全反射閉じ込め
型導波路と、 高誘電率媒質内にフォトニック結晶による孔を所定のパ
ターンで２つのグループに分けて配列され、前記全反射
閉じ込め型導波路の幅と同一又は略同一な幅を有して前
記孔を有しない線欠陥部が前記２つのグループの境界部
に形成され、前記線欠陥部に前記全反射閉じ込め型導波
路の一端が接続され、前記全反射閉じ込め型導波路の両
側に前記高誘電率媒質を突出させて保護部が形成されて
いるフォトニック結晶線欠陥導波路を備えることを特徴
とする導波路。5. A total reflection confined waveguide having a predetermined width and a predetermined length, and holes formed of a photonic crystal in a medium having a high dielectric constant and divided into two groups in a predetermined pattern. A line defect having the same or substantially the same width as the width of the waveguide and having no hole is formed at the boundary between the two groups, and one end of the total reflection confined waveguide is formed at the line defect. And a photonic crystal line defect waveguide in which a protective portion is formed by protruding the high dielectric constant medium on both sides of the total reflection confined waveguide.
JP2001172042A 2001-06-07 2001-06-07 Waveguide Expired - Fee Related JP3846228B2 (en)

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US10/162,764 US6795621B2 (en) 2001-06-07 2002-06-06 Waveguide comprising a connection of a photonic-crystal line-defect-waveguide to a total reflection confinement waveguide

Applications Claiming Priority (1)

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US7778509B2 (en) 2003-03-14 2010-08-17 Nec Corporation Method for incidence of light into a photonic crystal optical waveguide and structure thereof
WO2006073194A1 (en) * 2005-01-06 2006-07-13 Nec Corporation Optical waveguide, optical device and optical communication device
KR101012505B1 (en) * 2008-12-04 2011-02-08 인하대학교 산학협력단 Photonic crystal waveduide inlet structure
KR101107624B1 (en) 2010-07-02 2012-01-25 인하대학교 산학협력단 A interface structure between a photonic crystal waveguide and a strip waveguide with the modification of inlet holes for enhanced coupling efficiency
JP2014197837A (en) * 2013-03-04 2014-10-16 国立大学法人大阪大学 Terahertz wave connector, terahertz wave integrated circuit, waveguide, and antenna structure
JP2016004147A (en) * 2014-06-17 2016-01-12 日本電信電話株式会社 Optical circuit

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